The present invention relates to radar antenna systems and particularly to a pattern corrector for a conformal phased array monopulse antenna system.
In certain monopulse radar applications, such as aboard aircraft, it becomes advantageous to mount a phased array antenna onto the curved exterior surface of the host vehicle. Such a conformal phased array antenna however, produces a distorted radiation pattern when the beam is scanned off of broadside.
When the positions of the individual radiating elements on the curved surface of a conformal phased array antenna are projected onto a straight line, the element spacings on the projected line are shortened from those on the curved surface. The change is small at broadside, but increases as the angle of projection off of broadside increases. The shortened projected element spacings cause the effective array amplitude taper to become altered, thereby resulting in antenna pattern distortion. At scan angles other than zero degrees, the taper is skewed; the greater the scan angle, the greater the skewness. It is conceivable that the antenna pattern could be corrected by providing amplitude and phase adjustments at each of the individual radiating elements. However, such a solution would be unwieldy and highly impractical.